1. Field of the Invention
The present invention relates to a fuel cell, and a method for the production of a fuel cell.
2. Description of Related Art
In general, a fuel cell is known in which a cell stack in which a plurality of cells are stacked is housed in a box-shaped case. In many cases, the cell stack is held in compression in the stacking direction in the case. In general, each cell includes a membrane electrode assembly in which a pair of electrodes is located on both sides of an electrolyte, and a pair of separators is located on both sides of the membrane electrode assembly.
As a method for adjusting the compressive load in the stacking direction that is applied to the cell stack that is housed in the case of a fuel cell, Japanese Patent Application Publication No. 2002-358985 (JP 2002-358985 A) discloses a method for adjusting the compressive load on the cell stack by rotating screws from outside the case to adjust the axial forces of the screws. Japanese Patent Application Publication No. 2005-524214 (JP 2005-524214 A) discloses a method for adjusting the compressive load by interposing shim plates (spacer plates) between the case and the cell stack.
However, in the case of the method for adjusting the compressive load by adjusting the axial forces of screws, the cell stack is compressed by stress from the screws and the stress may not be uniformly applied to the entire surface of the cell stack. In addition, chips may be formed when the screws are screwed in. On the other hand, in the case of the method for adjusting the compressive load by interposing shim plates, the weight of the fuel cell increases by the weight of the shim plates and it is difficult to adjust the compressive load finely by changing the thickness or number of the shim plates. As described above, the methods for adjusting the compressive load on a cell stack that is housed in a case in a fuel cell still have room for improvement.